Understanding the long-term impact of deforestation on ecosystem structure and function of tropical forests may aid in
designing future conservation programs to preserve biodiversity and sustain ecosystem productivity. We examined forest
structure, tree species composition, litterfall rate, and leaf litter decomposition in a mid-successional forest (MSF) and an
adjacent mature tabonuco forest (MTF) in the Luquillo Experimental Forest of Puerto Rico. Whereas the MTF site received
limited human disturbance, the MSF site had been cleared for timber production by the beginning of this century and was
abandoned after hurricanes struck the Luquillo Mountains in the 1920s and 1930s. We found that the MSF was dominated
by successional tree species 50 years after secondary succession, and did not differ in tree basal area and litterfall rate from
the MTF. Leaf decomposition rate in the MSF was higher than in the MTF, but this differencew as small.O ur resultss how
that deforestation has long-term (over 50 years) influence on tree species composition and that recovery of leaf
decomposition processes in secondary forest is relatively faster than that of tree species composition.

Comprehensive analysis of land morphology is essential to supporting a wide range environmental studies. We developed a landforms model that identifies eleven landform units for Puerto Rico based on parameters of land position and slope. The model is capable of extracting operational information in a simple way and is adaptable to different environments and objectives. The implementation of the landforms model for land cover change analysis represents an advanced step towards understanding the expansion of urban areas and forest cover in Puerto Rico between 1977 and 1994. Expansion of urban areas has typically been associated with low and flat topographies. Forest recovery, on the other hand, has been associated with high elevations and steep slopes. Our study revealed that (1) nearly half of new developments occurred outside the plains, (2) almost all new forests occurred in mountain regions (but not on the steepest slopes), and (3) there are transitional and very dynamic landforms (the side slopes) that experience both important land development and forest recovery. Finally, we present additional examples of the landforms model applications, including vegetation mapping, physiography, and the modeling of vertebrate habitat distributions.